基于转子储能的全功率变速水电机组低电压穿越控制策略研究

Research on Low Voltage Through Control Strategy for Full Power VariableSpeed Operation Hydro-Generator Units Based on Rotor Energy Storage

全功率变速水力发电机组是水力发电机组变速运行主要方式之一,能更快速度响应电网功率变化需求,对间歇性与随机性强的新能源消纳具有重要意义,其机组的低电压穿越能力是保障机组稳定并网运行的关键。提出了一种基于机组转子储能的低电压穿越控制策略,充分利用水力发电机组转子储能能力强和机组输入功率可以调节的特点,采用转子储能和调速器调节吸收控制电网电压跌落期间的机组不平衡能量,并根据电网电压跌落幅值通过网侧变流器向电网提供无功电流支撑。建立了系统各部件的数学模型,通过仿真比对了提出的控制策略与传统的策略,仿真结果表明提出的控制策略能有效抑制直流母线过电压,并向电网提供无功电流支撑,提高了全功率变速水力发电机组的低电压穿越能力。

The full-power variable-speed hydropower generating unit is one of the main variable-speed operation modes of hydropower generation,which can respond to the changing demand of the power grid at a faster speed,and is of great significance to the absorption of new energy with strong intermittency and randomness.The low voltage-through capability of the hydropower generating unit is the key to ensure the stable operation of the grid-connected unit.This paper proposes a control strategy based on the rotor energy storage,which takes full advantage of the strong capacity of the rotor energy and adjustable characteristics of the unit input power.Rotor energy storage and governor are used to regulate and control the unbalanced energy of the unit during the voltage sag,and reactive current support is provided to the power grid through the converter on the grid side according to the voltage sag amplitude.The mathematical model of each component of the system is established,and the control strategy proposed in this paper is compared with the traditional strategy through simulation.The simulation results show that the proposed control strategy can effectively suppress the overvoltage of the DC bus,provide reactive current support for the power grid,and improve the low voltage crossing ability of the full-power variable speed hydropower generator unit.